What is colorblindness?

Color blindness is a consequence of the absence or malfunction of certain color-sensitive cells of the retina.

The retina - a layer of nerves at the back of the eye that converts light into nerve signals that send information to the brain. A person with color blindness has some problems in distinguishing such as flowers - red, green, blue, or combinations of these colors.


Usually, the eye has three types of cone cells, which are light-sensitive cells and are located in the retina. Each type is sensitive to red, green, or blue light. You see, regardless of the color when your cone cells differentiate the number of cells of the three primary colors. When one or more of these types of cells is absent or unable to function properly, you will not be able to see one of these three colors, or you can see the change of a color.
Cone cells are concentrated mainly in the central part of the retina (spot), to ensure clear, sharp color vision. They work best in relatively bright light, so it is difficult to distinguish colors in the dim light.

The term "color vision problem" is often used instead of color blindness because most people with color blindness may be little to distinguish colors. Some people with color blindness can not distinguish colors at all.

What causes color blindness?

Most of the problems associated with color, inherited genetically and is already present at birth.Other problems with the definition of color due to aging, illness, injury eye (acquired by vision problems), with the problems of the optic nerve, or with side effects of some drugs.

Legacy vision problems related to the definition of color, more common than acquired problems and affect men more often than women.

How to diagnose color blindness?

To measure the ability to distinguish colors, using different tests:

The most famous test - psevdoizohromatichesky test plate. During this test, you will be asked to look at the totality of colored dots and identify the sample, like a letter or number. Type of problems related to color vision, which you have, can often be determined by the way what samples you see or not see through a variety of plates used during the test.

For people with acquired color vision problems using the distribution of test items in color. The basis of this test is the distribution of subjects according to the color or shade. People who are colorblind, can not expand the color plates correctly.

How does it treat?


Inherited color vision problems can not be cured or corrected. Some acquired color vision problems can be cured, depending on the cause. For example, if the cataract causes problems with color vision, surgery to remove a cataract may restore normal color vision.

The problem with color vision may have a significant impact on human life. These problems can affect learning ability and reading, as well as significantly limit the choice of occupation rights.However, children and adults with color vision problems can learn to compensate for their inability to distinguish colors.

Symptoms may vary in color blindness. Different people see different shades of colors. You can not see the red, green and blue colors, or shades of these colors. If the problem of color vision is not so serious, you can not understand that you can see something else than a man who has normal color vision.

People with less severe color vision problems distinguish shades of colors. They may not be able to distinguish red from green, but can see blue and yellow.

People with serious problems of color vision can not distinguish colors at all. They see only shades of gray, chernogoi white.

Inherited color vision problems affect both eyes equally;

Acquired color vision problems can occur only in one eye or may affect one eye more than the other.

Inherited problems with color vision are usually present at birth and do not change over time.

Acquired color vision problem may change over time with the person's age or during the course of the disease.

Genetically inherited color vision problems.

Most of the problems associated with color vision, inherited genetically and is associated with the problems of the cone cells in the eye, which distinguishes color. Inherited color vision problems affect both eyes equally, usually present from birth and do not change throughout life.

Most common problems of color vision - the inherited problems in which very difficult to distinguish between red or green.

This problem affects approximately 8% of men and less than 1% of women. Suffice rare type of inherited problems, in which a person sees a blue and yellow shades of the same (both men and women).

Types of inherited color vision problems.

There are four main types of inherited color vision problems:

The most common type of color vision problem, called anomalous trihromasiey, occurs in people who have all three types of cone cone (to distinguish red, green, or blue), but are missing or incorrect number of one type of cone-cone, or a one type of cones is a lack of pigments, to perceive color.

People with these vision problems can see all three colors such as green, red and blue - but not as people with normal color vision. Thus, they see different shades of colors in a different way than people with normal color vision.
Another type of color vision problems, called dihromasiey happens when one of the three types of cones of the cone is missing. Thus, a person can only see two of the three colors.

Most people with this problem of color vision can detect the difference between blue and yellow flowers, but have problems in determining the difference between red and green colors. (Very few people in this category may see red and green colors, but do not distinguish between blue and yellow colors).
People with this type of disease more serious problems of color vision compared with the first type (anomalous trihromasiya).
The third type of inherited color vision problems, called the blue cone monohromasiey occurs when two of the cones of the cone (red and green) are absent.

This type of inheritance affects only boys and men.
Sight distance is often weakened, and the boys with the disease may be involuntary eye movements (nystagmus)
A boy or man with a blue cone monohromasiey distinguish only blue color of the entire spectrum of colors.
The fourth and the main type of inherited color vision problems, called achromatopsia, occurs when all three types of cones cone absent.

A person with this color vision problems can not see the color spectrum, but only shades of gray, black and white.
People who have this type of disease, may also have other vision problems, such as - a vision for distance and reading, sensitivity to light and lighting (photophobia).
This type of color vision problems is the rarest and most serious.
This disease is also called monohromasiey retinal rod, because man sees mainly due to strokes retina.
Genetics of inherited color vision problems.

Most color vision problems associated with genes that regulate the production of pigments in the cones cones that perceive color.

Genes tapered cones, responsible for the perception of red and green colors are in the X chromosomes. Women have two X chromosomes. Men have only one X chromosome and chromosome Y, and they inherit their X chromosome from the mother.

The man will be color vision problems in the red-green range, if the defective gene will be his only X chromosome. A woman may be defective gene in one of the two X chromosomes, which can cause color vision problems, and this happens far less often than men.
The woman, which has a genome of this type of color vision problems, there is a 50% chance of transmitting the gene her sons (because they inherit one of the two X chromosomes). Her daughters may be such a problem, if they inherit the defective gene on the X chromosomes and from mother and a father. This is much less probable case.
That is why color vision problems can occur through several generations in families who have a genetic predisposition to problems with color vision.

Genes responsible for the pigment of the cones of the retina and responsible for the vision of blue color, are not in the X chromosomes and are non-sexual chromosomes, which have both men and women. This means that the color vision problems associated with blue, occur with equal frequency in men and women. However, these types of color vision problems are relatively rare.

Acquired color vision problems.

In acquired color vision problems have many causes:

Aging may increase the chance of color vision problems. Vrezultate darkening of the lens with age, people are difficult to perceive the difference between dark blue, dark green and dark gray.
Side effects of certain drugs can cause temporary or permanent color vision problems.
Certain eye diseases such as glaucoma, macular degeneration, cataracts, or diabetic retinopathy, can cause temporary or permanent color vision problems. The treatment of these diseases may help to preserve or restore color vision.
The wound in the eye, especially in such parts as the retina (spot), or in the optic nerve, can cause color vision problems.
Acquired color vision problems:

Common in women as often as men. Inherited color vision problems are much more common in men.
May occur only in one eye or affect one eye more than the other. One eye may be the problem of color vision, and the other eye may be normal color vision.
May change over time, throughout a person's life or during illness or injury, the eye that cause this problem.
Often makes people unable to see the difference between blue and yellow.